/Engine/Source/Editor/BlueprintGraph/Public/BlueprintNodeTemplateCache.h
External systems can make changes that alter the memory footprint of the cache (like calling AllocateDefaultPins), and since we don't recalculate the cache's size every frame sometimes we need to update the internal estimate.
The new approximated total (in bytes) that this cache has allocated.
int64 RecalculateCacheSize()